Method of producing vinyl alcohol polymer fibers and products thereof



United States Patent IVIETHOD OF PRODUCING VINYL ALCOHOL POLYMER FIBERSAND PRODUCTS THEREOF Masakazu Matsumoto, Masayasu Maeda, and TetsuroOsugi, Kurashiki-shi, Japan, assignors, by direct and mesne assignments,of three-fourths to Kurashiki Rayon (30., Ltd., Kurashiki-shi, Japan, acorporation of Japan, and one-fourth to Air Reduction Company,gfnctirporated, New York, N.Y., a corporation of New No Drawing.Application May 26, 19-55 Serial No. 511,408

. 3 Claims. 01. rat-"45.5

The invention relates to the manufacture of waters'oluble filaments,fibers, yarns, threads and the like.

It is known that polyvinyl alcohol fibers as obtained by spinningwithout after-treatment, are more or less water soluble. However, theyhave not sufficient strength to be useful for textile purposes and otherindustrial applications.

It is a principal object of the invention to provide a fiber onpolyvinyl alcohol basis, which is useful as a textile fiber.

It is another object of the invention to provide a method for preparingwater soluble fibers on polyvinyl alcohol basis which have increasedmechanical strength.

Other objects and advantages will be apparent from a consideration ofthe specification and claims.

According to the invention, fibers which are soluble in water of 50 C.and below and have the strength required for textile manipulations areobtained from conjoint polymers of vinyl alcohol and allyl alcohol. Suchcopolymers are best obtained by the saponification of the copolymers oforganic vinyl esters with allyl esters or allyl alcohol. Suitable estersare the esters of lower aliphatic acids, particularly of acetic acid,but the esters of formic acid, propionic acid, butyric acid and the likemay also be used. Such conjoint esters are readily prepared andsaponified by conventional procedures. The obtained polyvinylalcohol-allyl alcohol copolymer dissolves in cold water and can be spunby the usual wet and dry spinning methods. In wet spinning, concentratedsolutions with above two thirds of the saturated solubility of thecoagulating salts, such as sodium sulphate or ammonium sulphate,

Patented Oct. 20, 1959 2 In wet spinning, a high allyl alcohol contentof the conjoint polymer may atfect the speedy coagulation in aconventional spinning bath. A preferred embodiment of the inventionconsists, therefore, in spinning together mixthe required minimum DP ofthe copolymer and its mixture with the homopolymer must be used above250.

must be used. The cold water solubility of the obtained Mol percentAllyl Al hol co 0 0.5 0.9 1. 8 2. 2 2. 6 3 3. 5 4.4 Dissolving Temp., O.70 61 54 30 23 20 17 14 Tenacity, g./d 3.4 3.3 2.5 2.0 3.0 3.0 2.0 2.52.9

The table shows that in order to be soluble in water of 50 C. and below,the fibers must contain an allyl alcohol content of at least about 2mole percent. The upper limit is about 10 mol percent, as with higherproportions of allyl alcohol the tenacity of the fibers decreases tosuch an extent that the fibers are no longer suitable for textilepurposes. Generally, the optimum content will be about 2.5 to 5 molpercent of allyl alcohol.

prevent the obnoxious puckering of seams.

Also, fibersprepared from such mixtures have the required tenacity andwater solubility.

The novel fibers are useful for specialty sewing threads, alone -ortogether with other fibers to obtain in woven material eifects whichcannot be produced by other means. Twisted with cotton or nylon fibers,a sewing thread can be made which will shrink to a predetermined degreeand When the novel fibers are twisted with a fully syntheticthermoplastic fiber, such as nylon, Dacron, and the like, a permanenttwist can be applied to said thermoplastic fibers by first setting thetwist and then washing out the polyvinyl alcohol-allyl alcohol fiber,thereby producing a permanently elastic fiber. Fabrics produced from thenovel fiber are, for instance, useful for the manufacture of watersoluble parachutes. As will be seen from the foregoing, the novel fiberopens up a vast field of new applications; for instance, in themanufacture of filter cloth, lace, knitted fabrics, and the like,effects can be obtained which cannot be produced by other means.

The following specific examples are given to illustrate the inventionbut they are not intended to limit it thereto; the parts are by Weight.

Example 1 291 parts of vinyl acetate and 9 parts of allyl acetate weremixed and polymerized in the presence of 0.6 part of benzoyl peroxide.After an about 5.0% polymerization was obtained, 100 parts of methanolwere slowly added, and the polymerization was continued until after 20hours, a polymer yield of was obtained. The copolymer was freed fromunreacted monomers, dissolved in methanol and cold sa-ponified by addinga methanol solution of caustic soda to the methanol solution of thepolymer. The polyvinyl alcohol-vinyl alcohol copolymer was obtained as awhite powder containing 3 mol percent of allyl alcohol and having a DPof 1160. The copolymer was dissolved in water to a 13% solution, whichwas spun into a saturated solution of Glauber salt. The obtained whitefibers had a tenacity of 3.3 g./d. and dissolved instantaneously inwater of 23 C.

Example 2 A vinyl alcohol-allyl alcohol copolymer was prepared accordingto the procedure set forth in Example 1. It contained 4.4 mol percent ofallyl alcohol, had an average DP of 700, and was soluble in water at 14C. 60 parts of said copolymer were mixed with 40 parts of vinyl alcoholhomopolymer having an average DP of 1630 and a saponification degree of99.8, which was soluble in water at 70 C. The mixture was dissolved inwater to a 15% solution, using the method described in Patent No.2,642,333. The obtained fiber had, after drying, a tenacity of 3.0 g./d.and was soluble in water at 30 C.

:3 Example 3 A 6% aqueous solution of a vinyl alcohol allyl-alcoholcopolymer containing 3 mol percent of allyl alcohol and having anaverage DP of 930 was spun to filaments by extruding the solutionthrough a spinneret into a column of hot air of l10120 C. The solidifiedfilaments had a tenacity of 1.5 g./ d. and Were soluble in Water at 22C.

As various embodiments of this invention may be made without departingfrom the spirit and scope thereof, it is to be understood that thisinvention is not limited to the specific embodiments thereof except asdefined in the appended claims.

We claim:

1. A fiber soluble in water at 50 C. and having a tenacity of at leastabout 1.5 g./d. comprising a vinyl alcohol-allyl alcohol copolymercontaining 2 to 10 mol percent of allyl alcohol.

2. A fiber soluble in water at 50 C. and having a tenacity of at leastabout 1.5 g./ d. consisting essentially of a mixture of a vinylalcohol-allyl alcohol copolymer References Cited in the file of thispatent UNITED STATES PATENTS 2,236,061 Izard et al. Mar. 25, 19412,332,896 DAlelio Oct. 26, 1943 2,424,838 Moffett'et al. July 29, 19472,611,754 Rudofi? Sept. 23, 1952 OTHER REFERENCES Elvanol,- copyright,1947, E. I. du Pont, pages 37-38.

2. A FIBER SOLUBLE IN WATER AT 50*C. AND HAVING A TENACITY OF AT LEASTABOUT 1.5 G./D. CONSISTING ESSENTIALLY OF A MIXTURE OF A VINYLALCOHOL-ALLYL ALCOHOL COPOLYMER WITH VINYL ALCOHOL HOMOPOLYMER ANDCONTAINING 2 TO 10 MOL PERCENT OF ALLYL ALCOHOL.